1. Technical Field
The invention relates generally to semiconductor processing, and more specifically, to detecting gaseous substances emanating from material used in semiconductor processing.
2. Background Art
In semiconductor processing, certain materials, such as resists of polymeric composition, may produce and emit a gaseous substance when irradiated or thermolyzed. If the gaseous substance is corrosive and/or present in a certain quantity, the substance may be damaging to the materials surrounding the resist. For example, when exposed to ultraviolet light, a negative resist used in masking a semiconductor device may produce and emit minute quantities of hydrochloric acid. Hydrochloric acid, when reaching a certain strength and when within a particular proximity to the lens in a stepper chamber, may corrode the magnesium coatings on the lens, thus damaging the lens. Although the quantity of the hydrochloric acid emitted from the resist may be minute, an accumulation of acid after a period of time may eventually accumulate to a corrosive amount.
Within the technology of lithography, acids may be detected on an exposed film or surface through the use of an indicating dye, which is in contact with the exposed film or surface. Examples of this type of acid detection are found in the following U.S. Patents: U.S. Pat. No. 5,441,850, "Imaging Medium and Process for Producing an Image," issued to Marshall et al.; U.S. Pat. No. 5,514,519, "Production of Three-Dimensional Objects," issued to Neckers; and U.S. Pat. No. 5,631,118, "Imaging Medium," issued to Gaudiana et al.
Although acids can be detected on a surface as described in the above-referenced patents, the patents do not disclose, nor recognize the need for, the detection of acids that are in a gaseous state, and the detection of such gaseous acids at a location that is spatially disposed from the exposed film or surface. Also, the above-referenced patents do not take in account the corrosive and cumulative effects of gaseous substances involved in semiconductor processes. Indeed, most acids detected in lithographical systems and tests therefor are not relevant in semiconductor processes.